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Hard Drive: CDC: WREN IIHH 94204-81 71MB 5.25"/HH IDE / AT

W R E N   I I H H   9 4 2 0 4 - 8 1    CDC
NO MORE PRODUCED                                      Native|  Translation
Form                 5.25"/HH              Cylinders    1032| 1024|  516|  745
Capacity form/unform    71/   80 MB        Heads           5|    8|   10|   11
Seek time   / track  29.0/ 5.0 ms          Sector/track   27|   17|   27|   17
Controller           IDE / AT              Precompensation
Cache/Buffer            32 KB LOOK-AHEAD   Landing Zone
Data transfer rate    9.375 MB/S int       Bytes/Sector      512
                      4.700 MB/S ext
Recording method     RLL                            operating  | non-operating
Supply voltage     5/12 V       Temperature *C        10 50    |    -40 70
Power: sleep              W     Humidity     %         8 80    |      5 95
       standby            W     Altitude    km    -0.305  3.048| -0.305 12.210
       idle          18.0 W     Shock        g         2       |     32
       seek          20.0 W     Rotation   RPM      3597
       read/write         W     Acoustic   dBA
       spin-up            W     ECC        Bit   56
                                MTBF         h      40000
                                Warranty Month
Lift/Lock/Park     YES          Certificates     CSA,SDA,FCC,IEC380,IEC435,...



  |+-+LED                                                  |XX Power
  |+-+                                                     |XX
  |                                                        |+-+
  |                                                        || | J2
  |                                                        |+-1
  |                                                        |+-+
  |                                                        |+-+Master
  |                                                        |1-+Slave
  |                                                        |XX
  |                                                        |XX 40 pin
  |                                                        |XX I/O
  |                                                        |.X J3
  |                                                        |XX
  |                                                        |XX
  |                                                        |XX
  |                                                        |XX1



Jumper setting

J2 for factory use.

 Master/Slave Present
 1 & 2  ON   Drive is master
        OFF  Drive is slave

 BA0/No Slave Present Jumper
 3 & 4  ON   For regular models, jumper, is present, must remain on.
             Drive will not operate correctly if jumper is removed.

For "C" models, jumper ON indicates no slave present; jumper OFF
means slave drive is present.

The 94204 is capable of operating on the AT bus in a daisy chained
configuration with a second drive/controller that operates in
accordance with these specifications. One drive is designated as
master and the other as the slave. Models 94204-65C, 94204-71C,
94204-74C and 94204-81C can be daisy chained in either configuration
with other compatible drives that conform to the proposed ANSI ATBUS

Selection of the Master drive is made by a jumper plug installed on
two pins on a connector header to the right of the 40 pin interface
connector at the rear of the drive. No jumper plug present means the
drive is the slave. When it is intended that a drive should be the
slave, do not store the removed jumper plug on any other pins of the
connector, as that will cause the drive to operate incorrectly.

Slave Present Selection
Slave Present Selection is made by removing the jumper from the pins
adjacent to the Master/Slave select jumper. A jumper plug installed
means that no slave drive is present.

 J3   DC Power and pin connector assignments
      +------------+   pin 1    +12 VDC
      | 1  2  3  4 |   pin 2    +12 Volts Return
      +------------+   pin 3    + 5 Volts Return
                       pin 4    + 5 VDC



Notes on installation

Drive mounting

     horizontally             vertically
   +-----------------+   +--+             +--+ +------------------+
   |                 |   |  +-----+ +-----+  | |                  | x
   |                 |   |  |     | |     |  | x+----------------+x
 +-+-----------------+-+ |  |     | |     |  | ||x              x||
 +---------------------+ |  |     | |     |  | ||  x          x  ||
                         |  |     | |     |  | ||    x      x    ||
      x           x      |  |     | |     |  | ||      x  x      ||
 +------x------x-------+ |  +-----+ +-----+  | ||       xx       ||
 +-+------x--x-------+-+ +--+             +--+ ||     x    x     ||
   |       xx        |                         ||   x        x   ||
   |     x    x      |                         || x            x ||
   +---x--------x----+                         |x                x|
     x            x                           x++----------------++x
      UNACCEPTABLE!                                UNACCEPTABLE!
      Never install PC board on the Top!

Drive Orientation
The permissible drive mounting orientation include operation in the
horizontal plane and in the vertical plane. Mounting with either end
down (front or rear) is not permissible. An angle of 15* up from the
horizontal (front end only) is acceptable for the horizontal orienta-

WREN 2HH (AT interface) is designed, manufactured, and tested with a
"Plug-in and Play" installation philosophy. Basically, this
philosophy minimizes the requirements for highly trained personnel
to integrate the WREN 2HH (At interface) into an OEM's system, wether
in a factory or field environment.

Cabinet cooling must be designed by the customer so that the ambient
temperature immediately surrounding the WREN 2HH (AT interface) will
not exceed temperature conditions.

Service Tools
No special tools are required for site installation or recommended
for site maintenance. The depot repair philosophy of WREN 2HH (AT
interface) precludes the necessity for special tools. Should field
repair of items external to the HDA be desired, one 6 point size
T10 Torx driver is required. This hand tool may be ordererd through
most commercial tool catalogs.

Air Cleanliness
The WREN 2HH (AT interface) is designed to operate in a typical
office environment with minimal environment control.

Physical Interface
The physical interface consists of single ended TTL compatible re-
ceivers and drivers communicating through a 40 conducter flat ribbon
nonshielded cable maximum length 24 inches (0.61 metre) using
asynchronous interface protocol.

 Interface cabling options
         |                  HOST               |
         |        I/O                          |
         +---------+--+  +----------+--+
         |   'AT'     |  |   'AT'      |
         |   WREN     |  |   WREN      |
         +------------+  +-------------+

If you have a 94204-xxC, then you can connect two different model
drives on the same host adapter. (i.e. a 94204-xxC and a 94354-xxx

If you do not have a "C" after the model number, then you can only
connects two similar WREN 2 94204-xx model drives.

DC Cable and Connector
The WREN 2HH (AT interface) receives DC power through a 4 pin rigth
angle connector mounted on the main circuit board. Recommended part
numbers for the mating connector are included below, but equivalent
parts may be used.

Type of cable: 18 AWG
Connector: AMP 1-480424-0
Contacts: AMP 60619-4 (Loose Piece); AMP 61117-4 (Strip)

Device Grounding
The WREN 2HH (AT interface) is shipped with the DC Logic ground and
the chassis ground joined together. These two ground planes may be
separated by repositioning the motor control board ground washer.

Note: If the grounds are to be separated, the washer must be oriented
so that it does not contact the ground run near the screw at any

System Ground Quick Connect Terminal
System ground may be connected to the Quick connect terminal.
Recommended part numbers for this connector and the mating ground
cable connector are listed, but equivalent parts may be used.

    Drive Connector Terminal: AMP  P/N 61664-1
    Cable Connector Terminal: AMP  P/N 62137-2

I/O Cable and Connector
The I/O connector is a 40 pin connector. The odd pins are located
along the edge of the printed circuit board with pin 1 leftmost. The
even pins are on the side away from the edge of the printed circuit
board. A key is provided by the removal of Pin 20. The corresponding
pin on the cable connector should be plugged. Seagate recommends
keying this connector to prevent the possibility of installing it
upside down.

Maximum I/O cable length is 24 inches (.61 metres).

Recommended part numbers for the mating connector are included below,
but equivalent parts may be used.

 Connector:          40 pin, 3M-3417-7000 (Strain relief 3448-2040)
 Cable:              Flat Cable (Stranded AWG 28) 3M-3365-40
                     Flat Cable (Stranded AWG 28) 3M-3517-40 (Shielded



General Description
The WREN 2HH (AT interface) drives are members of a family of low
cost, high performance, highly reliable, random access storage
devices designed to meet the needs of the OEM, AT (IDE) compatible,

The WREN 2HH (AT interface) has been developed as system peripherals
to the highest standards of design and construction. The WREN depends
upon their host equipment to provide adequate power and environment
in order to achieve optimum performance and compliance with
applicable industry and governmental regualations. Special attention
must be given in the areas of safety, power distribution, shielding,
audible noise control, and temperature regulation.

The WREN 2HH (AT interface) is a UL Recognized component per UL 478
and a CSA Certified product per CSA C22.2 No. 220-M1986. It also
meets the requirements of DIN IEC 380/VDE0806/8.81, DIN IEC 435/VDE
0805/11.84 and EN 60950/09.87.

The WREN 2HH (AT interface), as delivered, is designed for system
integration before use. It is supplied as a Class A Computing Device
per the FCC Rules and Regulations, Part 15, Subpart J governing EMI
of computing devices and the Radio Interference Regulations of the
Canadian Department of Communications.

The head, disc and actuator chamber (HDA) is environmentally sealed
at the factory. Air is recirculated within the HDA and passes through
a nonreplaceable filter to ensure the maintenance of a contamination
free disc/actuator environment.

The WREN 2HH uses a dedicated landing zone at the innermost
radius of the media thus eliminating the possibility of destroying or
degrading data by landing in the data zone.

The WREN 2HH incorporate an automatic shipping look which prevents
potential damage to the heads and discs caused by movements during
shipping and handling. The shipping lock is automatically disengaged
when power is applied to the drive.

The WREN 2HH (AT interface) decodes Track 0 location from the
dedicated servo surface thereby eliminating mechanical transducer
adjustments and related reliability concerns.

The WREN 2HH (AT interface) uses a high performance actuator assembly
consisting of a low inertia, balanced, patented, straight arm driven
by a highly efficient pancake coil assembly. This patended actuator
mechanism provides excellent performance with minimal power dissipa-

Media Description
The media used on the WREN 2HH (AT interface) has a diameter of
approximately 5 inches (130 mm). The aluminum substrate is coated
with lubricated ferrous oxide which permits the heads to contacts the
surface when starting and stopping.

Media defects are characterized as beeing either correctable or un-
correctable as a function of the type and magnitude of the media
flaw. A 56 bit error correction code is used to identify and correct
errors in the data read from the disc. In the WREN 2HH (AT interface)
media certification is performed using the following standards:

            An error burst of 11 bits or less is a correctable error.

            An error burst greater than 11 bits in length is an un-
            correctable error.

At the time of shipment from the point of manufacture, the WREN 2HH
(AT interface) recording surfaces will meet the following

       1. 948 total physical tracks per surface (94204-65/74).
          1032 total physical tracks per surface (94204-71/81).

       2. Track 0 to be error free on each data surface.

       3. 30 defects per surface maximum.

       4. Accumulative defects not to exceed one per megabyte, based
          on total available unformatted drive capacity.

       5. Unidentified correctable errors shall not exceed two per

Seek Time

                                          |WREN 2HH|
        Track-to-Track         msec. typ. |   5    |
                       Average msec. typ. |  29    |
                       Average msec. max. |  65    |
        Latency                msec. avg. |   8.34 |
 Seek time is defined as the time required from the receipt of a Seek
 Command by the WREN 2HH (AT interface) until the completion of the
 seek operation. Average seek time is determined by dividing the sum
 of the time for all possible seek movements by the total number of
 seek movements.

Spindle Speed and Latency
The spindle speed is 3597 0.5% r/min. The speed tolerance includes
motor performance and motor control circuit tolerances.

The average latency time is 8.34 milliseconds, based on a nominal
disc speed of 3597 r/min. The maximum latency time is 16.76 milli-
seconds based on a minimum disc speed of 3579 r/min.

Host/Drive Interface data transfer rate
Maximum instantaneous: 4,750 kbytes/s
Maximum average: 830 kbytes/s

Power Sequencing
Power sequencing is not required for the WREN 2HH. If the Delayed
Motor Start jumper configuration is off, the slave drive motor start-
up is delayed 20 seconds from power on.

50*F to 122*F (10*C to 50*C) operating ambient with a maximum
gradient of 18* F (10* C) per hour. Above 1000 feet (305 metres)
altidude the maximum temperature is derated linearly to 95* F (35*C)
at 10,000 feet (3048 metres). Cabinet packaging designs must provide
ample air circulation around the WREN 2 to ensure environmental
limits are not exceeded as a result of heat transfer from other
system components. Operating ambient for specification purposes is
defined as the environment immediately surrounding the WREN 2. The
temperature of the HDA is restricated to a maximum of 143*F (62* C)
during operation.

Write Precompensation Cylinder
The starting cylinder for write precompensation is controlled by the
contens of this register. The starting physical cylinder is 4 times
value in this register. This register is ignored by the WREN 2HH
(AT interface). Use of write precompensation is controlled by the

The following reliability specifications assume correct host/drive
operational interface has been implemented, including all interface
timings, power supply voltages, environmental conditions, and
appropriate data handling circuit to the host system.

MTBF 40,000 hours
Service Life 5 years
Preventive Maintenance None required

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